The uninterruptible power supply (UPS) is used to provide stable power to its load, thereby isolating the load from the power supply line, and avoiding the load from being affected by the interruption of the power supply line (including spikes, overvoltage, undervoltage and power outages). When the UPS is out of power, depending on the size of the battery, it can supply power to the load for several minutes to several hours. Uninterruptible power supply can also be understood as such a device: it specifically protects the load so that it will not be affected by unstable power lines. This is a way to ensure the reliability of its working life.

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